Question

work out the value of; 3x + 2y when x = 5 and y = -4

Answer 1

All you have to do is plug the numbers in so -
3(5) + 2(-4)
So 3 * 5 is 15, 
15 + 2(-4)
and 2 * -4 is -8.
 So 15 + -8 = 7.
So your answer would be 7 :)

Answer 2

3x5=15    2x-4=-8  -8+15=7